The importance of maintaining the surface of highways, driveways, parking lots, and airports in structurally enhanced conditions cannot be over-estimated. The dependency of both industry and individuals on the high structural quality of pavement surfaces is highly significant. Surface failures may become a serious problem if not maintained properly. When asphalt is laid down as a new product or as an overlay, it immediately begins to deteriorate under the influence of the external environment, load of trucks, cars, airplanes, various construction, underground water, temperature changes, and other conditions relating to weather.
Eventually, if the pavement is not cared for properly, it will be undermined, forming cracks of different sizes resulting in structural failure. It is important to maintain the asphalt in a condition where no or as little as possible undermining water is allowed below the asphalt or into the subsurface in order to prevent the subsurface of the asphalt from being washed away and having a decreased stability.
However, if the asphalt has no t been maintained properly, and the subsurface of the asphalt begins to deteriorate, traffic or any other load over the asphalt will have a tendency to crack the asphalt or weaken the asphalt to a point where cracks are easily formed.
Seams formed in the asphalt laying process may constitute another problem. Due to freezing, temperature change, or excess water allowed through the seams as well as other weather phenomena, the seam may eventually (within a year or two), depending on the sub-base, open up and leave a crack in the asphalt which usually runs along the seam. If the crack in the seam is not sealed within a reasonable period of time, water (from rain, snow, and other precipitation) may find its way underneath the asphalt between the layers of the asphalt. Changes in temperature, i.e., intermittent freezing and thawing, destruct the asphalt frames which also advances the deterioration process of the asphalt.
It is a known practice to fill cracks with sealers to repair the cracks in order to prevent further deterioration of the asphalt. Products such as commercially available rubberized asphalt, silicone rubber, cold tar, PVC, and neoprene have been used successfully in the repair of cracks in pavements. The selection of a proper sealer is contingent on the type of crack to be sealed and the end result desired.
Among the many techniques for sealing cracks in pavement two main methods have been typically used. One of the commercially used methods is a hot pour crack filling, where a sealing compound is heated and melted from a relatively solid brick state into a liquid state and maintained in a container with an oil jacket to insulate against heat loss. Being in a liquid stage the sealer is pumped into the crack through a hose and is applied around the crack as well as over the crack area. The machines for applying sealant to the crack using the hot pour crack filling method are relatively expensive, with the cost possibly ranging from $5,000.00 to $25,000.00. The process is extremely time consuming, because it takes about an hour to an hour and a half to heat the block of sealer to transform it into a liquid form, and then takes several hours to cool the sealer applied to the crack.
Another method of applying the crack sealer is what is referred to as a cold pour crack filling. According to this method, which is less expensive than the hot pour crack filling, the sealant is pumped out of 55 gallon drums and applied to the crack through a hose. Afterwards, the sealant is typically squeegeed by a worker on the job site.
However, use of a 55 gallon drum on any one job, presents a serious problem. Once the 55 gallon drum is opened and exposed to the air, the surface of the material in the drum begins to solidify. The cold pour sealant is a water-based material, in which water dissipates and dries upon exposure to the air, thus the process of hardening and thickening of the cold pour sealant is rapid. The sealant from the 55 gallon drum usually is pumped to a hopper, from which the sealant is applied to the crack.
However, the process of quick solidification of the sealant when the sealant hardens means that time flexibility is diminished. Additionally, if the sealant has dried in the hopper, it is difficult and time consuming to clean the hopper for further use. Usually, cleaning of the typical cold pour machine takes about an hour, and results in significant lost time in the overall process.
In order to obviate this problem some companies producing sealants, fill the sealant in five gallon plastic buckets, which are covered to prevent hardening of the sealant within the bucket.
Crack sealing machines come in a variety of different styles, types, designs, and dollar factors. For example, a crack sealer machine, described in U.S. Pat. No. 4,653,424, includes a support frame, a tank for holding a crack filling medium, a squeegee, and a handle regulating the squeegee and the flow of cracking filling medium from the tank. As described above, with respect to cold pour crack filling, sealant is loaded into the tank, which forms a part of the machine, and is inconvenient with respect to time lost for cleansing and washing of the hardened sealant left after the job is done.
Another machine for dispensing sealant into cracks in pavement, described in U.S. Pat. No. 4,575,279, includes a container mounted on a movable frame. The container has a dispensing opening in a bottom wall and a valve assembly in the container itself to control flow of sealant from the container. A roller and squeegee are mounted under the container for spreading the material after it has been dispensed. Similar to all other typical cold pour crack filling methods known in the art, the container after the job is done must be cleaned of the sealant which is inconvenient and time consuming.
Despite the existence of a variety of machines dispensing sealant to cracks in pavement, different techniques for maintaining the surface of pavement in proper shape, and many sealants available in the commercial marketplace, there has not yet been developed a machine and technique which would avoid time consuming cleaning of the hoppers in machines to prevent clogging of the system.
A machine for dispensing a sealant compound and technique for maintaining the surface of pavement spared of disadvantages of the prior art machines and techniques is thus a system which is needed in the industry to minimize labor requirements.